Which of the following is not generally observed in a geomagnetic storm?
Charged particles streaming out from the Sun
Fluctuations in the Earth’s magnetic field
Disruption of electrical power transmission
Disruption of microwave propagation
A device that reverses magnetic field polarity to keep a dc motor rotating is
A solenoid
An armature coil
A commutator
A field coil
When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
Increases
Decreases
Remains constant
Reaches zero
For a given wirewound core, an increase in current through the coil
Reverses the flux lines
Decreases the flux density
Increases the flux density
Causes no change in flux density
Which statements are correct?
Charges of opposite sign attract one another and charges of the same sign repel one another. Total charge in an isolated system is conserved. Charge is quantized.
Charges of opposite sign repel one another and charges of the same sign attract one another. Total charge in an isolated system is conserved. Charge is quantized.
Charges of opposite sign attract one another and charges of the same sign repel one another. Total charge in an isolated system is not conserved. Charge is quantized.
Charges of opposite sign repel one another and charges of the same sign attract one another. Total charge in an isolated system is ot conserved. Charge is not quantized.
No correct answer
When a box rests on the floor, it is acted upon by the gravitational and the _________________ force.
Centrifugal
Acceleration
Normal
Inertia
Friction
Motion is produced by
All forces
Unbalanced forces
Balanced forces
The absence of force
None of them
In inelastic collision between the two bodies __________.
Only momentum of the system is conserved
Only the kinetic Energy of the system is conserved
Both the kinetic Energy and Momentum of the system remain the same
Total energy is not conserved
In elastic collision between the two bodies __________.
When the force and displacement are parallel to each other, then work is __________.
Minimum
Maximum
None of these
Depends on force magnitude
In rotational motion, the quantity, which plays the same role as the inertial mass in linear motion, is called ___________.
Angular momentum
Moment of inertia
Torque
Center of mass
A sound wave can be characterized as
A transverse wave
A longitudinal wave
A transverse wave or a longitudinal wave, depending on the nature of its source
One that carries no energy
A wave that does not require a medium to be transmitted from one place to the other
A woman sits on a spinning stool with her arms folded. When she extends her arms, which of the following occurs
She increases her moment of inertia, thus increasing her angular speed
She increases her moment of inertia, thus decreasing her angular speed.
She decreases her moment of inertia, thus increasing her angular speed
She decreases her moment of inertia, thus decreasing her angular speed
Her angular speed remains constant by conservation of angular momentum
The ability of a material to remain magnetized after removal of the magnetizing force is known as
Permeability
Reluctance
Hysteresis
Retentivity
The induced voltage across a stationary conductor in a stationary magnetic field is
Zero
Reversed in polarity
Increased
Decreased
When a solenoid is activated, the force that moves the plunger is
An electromagnetic field
A permanent magnetic field
Varying voltage
A steady current
If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
Remains unchanged
Reverses polarity
You charge parallel-plate capacitor. When you pull the plates apart to a larger separation and battery remains connected to the capacitor
Remains the same
Alternates
Changes in an unpredictable way
Induction current opposes the reason causing it. It is the shortest formulation of
Einstein’s law
Lentz law
Biot-Savart law
Faraday’s law
Ampere’s law
Paramagnetism is closely associated with
The torque
The force exerted by electron dipole moments on each other
The tendency of electron dipole moments to align with an applied magnetic field
The exchange force between electrons
The tendency of electrons dipole moments to align opposite to an applied magnetic field
The thermal conductivity is the analog to:
Thermal expansion
Resistivity
Elasticity
Diffusivity
Viscosity
Resistance of metals in classical theory of electric conductivity is caused by
Collision of free electrons with dislocations or clasters
Collision of free electrons with impurity atoms in internodes
Collision of free electrons with each other
Collision of free electrons with vacancy defects
Collision of free electrons with ions of crystal structure
Electric theory of dispersion was evaluated by:
Lorentz
Newton
Einstein
Minkovsky
Maxwell
Loop is uniformly rotating with angular velocity ω in uniform magnetic field. Loop has N coils and area of the loop is S. Rotating axis lies on loop’s plane and perpendicular to induction. What is the maximal EMF appeared in the loop:
NBS/2
NBS
NBScos(wt)
NBSw/2
NBSw
An electrton traveling with speed v around a circle of radius r is equivalent to a current of:
evr/2
ev/r
2πer/v
2πev/r
ev/2πr
An electromagnetic field propagates in +x direction. The electric field at a point in space is momentarily oriented in –z direction. The magnetic field at that point is momentarily oriented in
–y direction
+y direction
+z direction
+x direction
-x direction
In RLC circuit angular frequency of AC source rises. Inductive reactance
Oscillates about certain value
The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might be due to:
A large capacitance
A small capacitance
A large resistance
A small resistance
A large inductance
Intrinsic semiconductors are
Materials doped by impurities
Pure elemental materials without impurities
Materials doped by donor impurity
Materials doped by acceptor impurity
Any materials
In a charge-free region of space, closed container is placed in an electric field. A requirement for the total electric flux through the surface of the container to be zero is that
The field must be uniform
The container must be oriented in a certain way
The container must be symmetric
The requirement does not exist – the total electric flux is zero no matter what
